Implement the log delivery target (closes #70)

internal/delivery/engine.go

@@ -1006,8 +1006,11 @@ func (e *Engine) deliverLog(
 		"webhook event delivered to log target",
 		"delivery_id", d.ID,
 		"event_id", d.EventID,
+		"webhook_id", d.Event.WebhookID,
+		"entrypoint_id", d.Event.EntrypointID,
 		"target_id", d.TargetID,
 		"target_name", d.Target.Name,
+		"outcome", database.DeliveryStatusDelivered,
 		"method", d.Event.Method,
 		"content_type", d.Event.ContentType,
 		"body_length", len(d.Event.Body),

internal/delivery/engine_test.go

@@ -1,6 +1,7 @@
 package delivery_test
 
 import (
+	"bytes"
 	"context"
 	"database/sql"
 	"encoding/json"
@@ -435,6 +436,91 @@ func TestDeliverLog_ImmediateSuccess(t *testing.T) {
 	assert.True(t, result.Success)
 }
 
+func TestDeliverLog_StructuredLogFields(t *testing.T) {
+	t.Parallel()
+
+	db := testWebhookDB(t)
+
+	var logBuf bytes.Buffer
+
+	e := delivery.NewTestEngine(
+		slog.New(slog.NewTextHandler(
+			&logBuf,
+			&slog.HandlerOptions{Level: slog.LevelDebug},
+		)),
+		&http.Client{Timeout: 5 * time.Second},
+		1,
+	)
+
+	event := seedEvent(t, db, `{"log":"structured"}`)
+
+	dlv := seedDelivery(
+		t, db, event.ID, uuid.New().String(),
+		database.DeliveryStatusPending,
+	)
+
+	d := &database.Delivery{
+		EventID:  event.ID,
+		TargetID: dlv.TargetID,
+		Status:   database.DeliveryStatusPending,
+		Event:    event,
+		Target: database.Target{
+			Name: "structured-log",
+			Type: database.TargetTypeLog,
+		},
+	}
+	d.ID = dlv.ID
+
+	e.ExportDeliverLog(db, d)
+
+	// The delivery is marked delivered and a success
+	// DeliveryResult with no HTTP status is recorded,
+	// mirroring the other target types' bookkeeping.
+	var updated database.Delivery
+
+	require.NoError(t, db.First(
+		&updated, "id = ?", dlv.ID,
+	).Error)
+
+	assert.Equal(t,
+		database.DeliveryStatusDelivered, updated.Status,
+		"log target should immediately succeed",
+	)
+
+	var result database.DeliveryResult
+
+	require.NoError(t, db.Where(
+		"delivery_id = ?", dlv.ID,
+	).First(&result).Error)
+
+	assert.True(t, result.Success)
+	assert.Equal(t, 0, result.StatusCode,
+		"log target should not have an HTTP status",
+	)
+
+	assertLogFields(t, logBuf.String(), event, "structured-log")
+}
+
+// assertLogFields checks that a log target's structured
+// log line carries the required fields: event id,
+// webhook/entrypoint, target name, and outcome.
+func assertLogFields(
+	t *testing.T,
+	logged string,
+	event database.Event,
+	targetName string,
+) {
+	t.Helper()
+
+	assert.Contains(t, logged, "event_id="+event.ID)
+	assert.Contains(t, logged, "webhook_id="+event.WebhookID)
+	assert.Contains(t,
+		logged, "entrypoint_id="+event.EntrypointID,
+	)
+	assert.Contains(t, logged, "target_name="+targetName)
+	assert.Contains(t, logged, "outcome=delivered")
+}
+
 func TestDeliverHTTP_WithRetries_Success(t *testing.T) {
 	t.Parallel()